Idrija, march 2003
HEALTH SAFETY PROGRAMME FOR
WORKERS EXPOSED TO HG°
ENVIRONMENTAL POLLUTION IN
THE IDRIJA REGION AND OVER A
BROAD AREA
Tatjana Dizdarevic, B.S.M.E.
Idrija Mercury Mine
1
Idrija
2
Introduction

Mercury was
discovered in y. 1490

500 years of mining
and smelting

In y. 1994 the ore
excavation and Hg
production stoped

The Mine will be shut
down in 2006
3
Important data






Hg content in ore: 0,1 – 10%
monomineral ore deposit: 70%
HgS and 30%Hg
12 mill. tons of ore was excavated
153.309 tons of Hg was extracted
107.692 tons of commercial Hg
losses: 44.616 tons of Hg
4
Closing-down Programme



The Long-term closing down Programme
for the gradual, complete and permanent
shut down of the Idrija Mine was
prepared in 1986, addopted in 1987 and
approved in 1989
The results of investigations and closing
down works through last few years
indicate that the concept of the mine’s
shutdown, was wll chosen
 thus ensuring the safety of the town
above the pit
5
Closing-down works in the
mine


gradually from the lowest
level upwards towards the
surface
backfilling (20.512 m of
galleries, 120.785 m3 concrete)

injecting (37 locations 
43.856 m of boreholes, 70.177
m3 of grout)

flooding of the pit (up to the
4th level)
6
WORKING LOADS AND MERCURY
CONCENTRATIONS IN THE PIT AND IN THE
SMELTING PLANT













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Physical loads
(dynamic and static)
Pulmonal ventilation
Air temperature
Relative humidity
Effective temperature
Dust concentration
(respirable part)
% free SiO2 in dust
Ionising radiation
Gama dose-rate
Carboniferous shale
Bituminous shale
5 - 9 Kcal.min-1
Radon concentrations
Radon daughters
700 - 1500 Bq.m-3
1.5 J.m-3 (0.07 WL)
24 - 33 L air.min-1
15 - 30 oC
70 - 92 %
15 - 27.8
30 - 70 mg.m-3
10 - 30 %
0.15 -0.20 Gy.h-1
up to 1 Gy.h-1
7
WORKING LOADS AND MERCURY
CONCENTRATIONS IN THE PIT AND IN
THE SMELTING PLANT
Mercury concentrations in the pit and in the smelting plant
The pit
cinnabar ore (HgS) excavations
native mercury ore excavations
The smelting plant
“less hazardous jobs”
“more hazardous jobs”
0.10 mgHg0.m-3
0.10 - 1.00
2.00 mgHg0.m-3
0.00-0.10 mgHg0.m-3
 0.10 -2.50
 3.00 mgHg0.m-3
Type of workers’ exposure
intermittent workers’ exposure to high Hgo concentr.
8
MAJOR PROBLEMS RELATED TO THE
TECHNICAL AND HEALTH PROTECTION OF
MINERS AGAINST MERCURY HAZARDS IN THE
PERIOD BEFORE 1964

In this period Hg concentrations (mg.m-3) were not regularly
monitored at all workplaces in mine areas with native Hg by
means of measurements;

workers were assigned to workplaces with increased Hg
concentrations without consideration for their previous
exposure to Hg;

deficient technical protective measures;

workers did not use personal safety equipment;

the Technical Service assigned workers to workplaces with
increased Hg concentrations without consulting the Health
Service;

the Health Service did not monitor the state of health of
workers during regular exposure;

health supervision did not include biological monitoring.
9
HEALTH AND SAFETY PROGRAMME FOR WORKERS
EXPOSED TO ELEMENTAL MERCURY AT THE
IDRIJA MERCURY MINE
(Kobal, Dizdarevič, 1997)

Regular monitoring of mercury concentrations at workplaces in the pit
and smelting plant;

Improvement of technical measures for the reduction of mercury
concentrations at workplaces in areas with native mercury;

Continuous use of personal safety equipment by workers exposed to
mercury;

Regular and controlled rotation of workers from hazardous to
nonhazardous workplaces and reduction of their exposure to mercury
from 8 to 6 and even 4 hours daily;

Regular monitoring of external exposure of individual workers and
estimation of cumulative monthly external exposure;

Medical surveilance and estimation of workers’ specific ability for work
at workplaces with increased concentrations of Hg vapours.
10
CONTROL OF WORKING ENVIRONMENT
Air Measurements and Mercury Emission Controls
Instant reading methods (quantification of mercury vapours):
Mercury vapour Meter - Beckmann K-23
range 0.005-0.1 mg.m-1, and 0.003-3.0 mg.m-3
repeatability + 10%
Mercury vapour Indicator - MVI Shawcity
range 0.00 - 2.00 mg.m-3, sensitivity 1g.m-3
repeatability + 5 %
Methods with separate sampling (quantification of total mercury):
acido-oxidising media (KMnO4), hopcalite, activated
charcoal, gold traps.
Samples are analised with cold vapour atomic absorbtion
spectrometrie (CVAAS) and with neutronic activation
analizes (NAA).
11
TECHNICAL PRECAUTIONS
Ventilation
This technical measure includes:
efficient front area ventilation and
indirectly a reduction of the temperature of air in the pit.
Q  300 - 400 m3 air ..... air quantitiy
F  10 m2 .... the cross-section of mine’s gallery
T
... (oC) as low as possible
temperature of the input air)
(the
l = 4F .... (m) the distance between the front
area and the ventilation pipe
12
TECHNICAL PRECAUTIONS
Ore processing technology

Developement of a new underhand mining method with
cemented backfill for extracting mercury ore from
carboniferous shale containing native mercury.

With the introduction of a new method of excavation, the
mercury concentrations in the pit air decreased for about
30%.

The reduction of the active vaporization surface reduces
the emission of vaporized mercury, which essentialy
contributes to the reduction of mercury concentrations in
pit air.
13
TECHNICAL PRECAUTIONS
Calcium polysulphide solution
(CaSn)
Hg + CaSn  HgS + CaSn-1
14
TECHNICAL PRECAUTIONS
Personal protection equipment

introduction of mask with mercury vapour filter for
hazardous works in the smelting plant after 1952;

use of isolating apparatures in particularly hazardous
works;

after 1965 the introduction of Dr ger half-masks with M
105 St. filters at all workplaces in the pit where Hg
concentrations in air exceeded 0.1 mg.m-3;

in 1984 AH6-Airstream Racal safety helmets with
AS60502 filters comprised of two layers of active
charcoal began to be used at all workplaces with
increased concentrations of Hg vapours.
15
TECHNICAL PRECAUTIONS
Personal safety equipment
Air-purifing helmet
absorbing filter
AH6-Airstream,
RACAL,
with
mercury
Calculation of useful life of filter AS60502 (estimation of
load):
The cumulative load is:
Bmax = cn  tn
cn ....... daily concentrations of Hg vapours
tn ...... duration of filter’s(miner’s) exposure to a certain
Hg concentration
When 1200 points are attained, the filter is to be replaced.
16
EXTERNAL MONTHLY EXPOSURE
INTENSITY
(AMI)
The Allowable Monthly exposure Intensity (AMI) is determined on the basis
of the assumption that a worker can work in an area with
concentrations of Hg vapours up to 0.1 mg.m-3 air without safety
equipment for a period of 8 hours daily for an average period of 26
days (the basis of calculating AMI was the maximum allowable daily
exposure to Hg):
AMI = 0.1 mg.m-3  8 hours  26 days/month =
= 20.8 points
The allowable monthly exposure intensity is thus assessed at 20.8 points,
which a worker is not allowed to exceed while working in hazardous
areas. In practise, the mine’s Technical Service calculated the monthly
allowable exposure time (MI) in the following way:
MI =  cn  tn
cn ....... daily concentrations of Hg vapours
tn ....... duration of miner’s exposure to a certain Hg concentration
17
MEDICAL SURVEILLANCE OF WORKERS
EXPOSED TO ELEMENTAL MERCURY
Target medical examination
(screening test)


Evaluation of typical nonspecific symptoms and signs (related to
“micromercurialism”);

Evaluation of current health contraindications to Hg exposure;
Timing of evaluation: before, during (once per week) and after exposure.
External exposure evaluation


Annual exposure data
• (time, concentration, Alowable Monthly exposure Intensity AMI);

Current exposure data
• (time, concentration, Monthly exposure Intensity- MI);
Timing of evaluation: before, during and after exposure.
18
MEDICAL SURVEILLANCE OF WORKERS
EXPOSED TO ELEMENTAL MERCURY
Biological monitoring

Cumulative internal dose evaluation
Urine mercury: morning urine, 18 or 24-hour urine samples;
timing of evaluation: before exposure.

Current internal dose evaluation
Urine mercury: post-shift urine spot samples;
timing of evaluation: during exposure 1 - 2 times per week;
Blood mercury (workplaces with high mercury concentrations);
timing of evaluation: during exposure - at the end of the week.
19
MEDICAL SURVEILLANCE OF WORKERS
EXPOSED TO ELEMENTAL MERCURY
Biological monitoring

Our recommended temporary Health based Biological Limit Value
(BLV)

BLV for workers intermittently exposed to Hg - 4 hours per day at
average pulmonal ventilation 27 L.min-1 (Kobal 1991).

Blood mercury:
35 g/L

Urine mercury*:
at 68% confidence limit
at 95% confidence limit
60 g/L
100 g/L**
135 g/L**


(upper limit)
(upper limit)
_______________________
* Correction of urine mercury concentration for specific gravity 1024
(Barber, Wallis 1986).
** U-Hg prediction based on B-Hg value 35 g/L,
yU-Hg= 1.35 x + 14.3, r = 0.68, P = 0.000,
standard error of predictions sy= + 37.7 g/L.
20
Environmental pollution
The realities of mercury pollution

The ecolgical flap over mercury poisoning has
already cut deeply into the metal’s traditional
markets ….

Lesson of Minamata Disease

Mercury Contamination in Iraq

Mercury Contamination in the Amazon
(Another Minamata?)
21
Environmental pollution in Idrija
Region
(monitored since 1970)




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Hg in air
Hg in water
Hg in sediments
Hg in soil
Hg in plants
Hg in animals
Hg in humans
Hg in old dust
22
Environmental pollution in Idrija
Region
500 years of mining activity

3.000.000 m3 of ore and gangue

total production of 150.000 tons of Hg

110.000 tons (commercial Hg )

40.000 tons (disipated into the
environment, i.e. 20 kg Hg/day)
23
Hg production in Idrija Mercury Mine
1490 - 1995 (Mlakar 1974, Cigale 1997)
Ore (t)
Period
1490-1580
1509-1785
1786-1945
1946-1960
1961-1977
1983-1995
1490-1995
Hg in ore (%)
36 000
217 867
5 892 113
1 871 054
3 957 911
231 279
12 206 224
1.00
17.00
1.48
0.42
0.23
0.24
Recovery
(%)
50
65
75
85
91
92
Hgcomm (t)
180
24 074
59 350
6 693
9 230
547
100 074
Total Hg production in Idrija Mercury Mine
1490 - 1995 (Cigale 1997)
Hg production
Hg (cinn. & other prod.)
TOTAL
Ore (t)
12 206 224
551 508
12 575 732
Hg in ore (t)
Hgcomm (t)
134 313
100 074
10 516
7 618
144 829
107 692
24
Average mercury concentrations
in the air in Idrija
Year
ngHg/m3 air
1971
1972
1974
1986
1990
1991
1992
1994
1999
2000
2001
2002
2000
4535
435
290
57
250
101
2158
20
14
10
12
20
25
Distribution of Mercury in the
Athmosphere over Idrija (M. Gosar et al., 1997)
Hg
( ng/ m3)
Idrija
FROM:
Gosar, M., Pirc, S., Šajn, R., Bidovec, M., Mashyanov, N.R. & Sholupov S.E.
1997: Distribution of mercury in the atmosphere over Idrija, Slovenia,
Environmental geochemistry and health, 19, 101-110.
26
Average mercury
concentrations in soil in
Idrija (mgHg/kg)
Earth crust
0.02
Slovenia
0.16
IDRIJA
1970 (Byrne & Kosta)
1991 (Hess)
52 - 315
0.2 - 148
1999 (Mercury Mine)
4 - 222
27
Hg in soil (Gosar M., PHD thesis, 1997)
Hg in soil
SP. IDRIJA
IDRIJA
data from Hess, 1992
geochemical map from Gosar., 1997 (Unpubl. PhD. thesis)
28
Pollution of Pit and Surface
Waters
Pit water
Period
1994
1999
2000
2001
2002
ngHg/L
2 - 547
1102
428
468
428
mgFetot/L
0.02 - 15
1.97
1.11
1.44
1.73
mgSO4/L
16 - 6400
1647
888
894
588
MAC
10.000
2.0
1000
Location
Idrijca River –
200 m before pit water outlet
Pit water
Idrijca River –
500 m after pit water outlet
unpolluted underground waters (Rose
et.al.,1979)
Year
1999
2002
1999
2002
1999
2002
ngHg/L
14
34
1102
428
103
62
mgFe/L mgSO4/L
0.06
4
0.04
8
1.97
1647
1.73
588
0.08
34
0.07
18
20
29
Mercury (dissolved) in the Surface
Water of Gulf of Trieste
(M. Horvat et al. Sept. 1995, surface water,)
N
0
10 km
ITALY
45.50
SLOVENIA
Isonzo
river
45.45
4.50
4.00
45.40
3.50
TRIESTE
3.00
2.50
45.35
2.00
Koper
1.50
Piran
1.00
45.30
Drag
o
13.25
13.30
13.35
0.50
nja
13.40
13.45
13.50
30
Smelting plant
1860 - 1970
31
Smelting plant
1980 - 1995
32
Mercury in Air - smeltery
Year
ngHg/m3 air
Author
1971
1972
20 000
8 500
Byrne& Costa 1970
Inst.Jožef Stefan 196971
Kavčič 1974
1986
~290
Mercury Mine
1990-92
1994
1998
1999
~150
4 078
400 – 3 000
114
Miklavčič
1991
1 000
Mašjanov & Šolupov
Mercury Mine
Mercury Mine
WHO*
*the limit value of Hg in air for residential areas
33
Smelting plant today
34
Remediation
35
Pront area – outcrop of ore deposit
36
Pront area (1999)
Location
non
contaminated
area
Pront area
Near smeltery
smokestack
mgHg/kg
soil
ngHg/m3
air
4.03
4.4
721.7
10.2
212.9
114.5
37
Mercury in plants
Plant
Carrot
Onion
Potatoe
Bean
Beetroot
Tomatoe
Cabbage
ngHg/g fresh weight
800 – 89
68,7 – 3,9
37,4 – 3,6
16,9 – 1,3
13,9 – 1,9
17,1 – 3,3
10,8 – 9,3
38
Mercury in animals
tissues
Animal Hgtot (ppm) MeHg (ppm)
Fish
1.45
0.92
MAC
0.50
Roe deer tissues and hairs: 100-times higher
values of Hgtot and MeHg in comparison with
control group.
39
Conclusions



Results 
Environment rehabilitation
measures
Reduction of loads on the
population
40
41